75991681 has 2 divisors, whose sum is σ = 75991682. Its totient is φ = 75991680.

The previous prime is 75991631. The next prime is 75991703. The reversal of 75991681 is 18619957.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 70308225 + 5683456 = 8385^2 + 2384^2 .

It is a cyclic number.

It is not a de Polignac number, because 75991681 - 2⁹ = 75991169 is a prime.

It is a super-2 number, since 2×75991681² = 11549471162411522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (75991631) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37995840 + 37995841.

It is an arithmetic number, because the mean of its divisors is an integer number (37995841).

Almost surely, 2^75991681 is an apocalyptic number.

It is an amenable number.

75991681 is a deficient number, since it is larger than the sum of its proper divisors (1).

75991681 is an equidigital number, since it uses as much as digits as its factorization.

75991681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 136080, while the sum is 46.

The square root of 75991681 is about 8717.3207466515. The cubic root of 75991681 is about 423.5669026789.

The spelling of 75991681 in words is "seventy-five million, nine hundred ninety-one thousand, six hundred eighty-one".